Geothermics - Black Gold For Everybody!
Geothermics - the gold mine, which everybody has at home. Why do closed geothermal systems (geothermal probes) have clear advantages and should be in the first place when selecting heat pump systems?
With the correct configuration of the geothermal probe, the heat pump and the heating system, the geothermal systems obtain the highest efficiency. In practice these systems achieve an operating figure bigger than four. To achieve these very good operating figures, the whole system has to be adjusted in an optimal way. It is very important, that all trades, as e.g. the planner of the heating system, the drilling company, the heating contractor, the heat pump manufacturer, the general construction company, the architect and finally the building owner himself cooperate in an optimal way. Unfortunately this is not always the case. In the opinion of Erdwärme-Zeitung.de it is also a reason, why there are seemingly bad functioning heat pump systems. Only if all systems are well adjusted, it will help the wallet and the environment.
The geothermal energy flows with regional differences and it flows very slow ( the geothermal heat flow for Dresden is ca. 0,060 W/m⊃2;) For this reason the professional calculation and configuration of the geothermal probe is such decisive. They have to be in line with the heating load of the building, because the higher the temperature of the incoming brine, the more efficient the heat pump will work. The most important feature for the comparison with the air heat pump is the temperature of the heat source. Air heat pump systems always face the problem that the temperature of the heat source strongly differs ( autumn, winter, day, night). The temperature of the heat source has a great influence on the efficiency of the heat pump system. Constant temperatures of the heat source are only provided by the earth. Moreover geothermal probes are maintenance free. Once professionally installed, they will supply safe energy for many decades. A table of a producer of pipes shows that the long period creep resistance of PE 100, the material which is used for geothermal probes equals to ca. 100 years at a pressure of max. 15.7 bar and a temperature of 20 degrees. Please note that it reaches only 15 years at a temperature of 50 degrees. If energy of solar plants shall be fed into the underground, this has to be taken into consideration during the planning.
For water - water heat pump systems the planning and the production requires much bigger efforts. Many factors, as the water volume, the well' s diameter and construction, the well' s depth, the quality and the temperature of the ground water, the lowered level of the ground water during the withdrawal of water have an influence on the efficiency of these systems. E.g. The water - water heat pump WI 14 TE from Dimplex requires 3.3 cbm of water per one hour. This water volume has to be provided during the complete heating season. The productivity strongly depends on the geological conditions on site. From our point of view at Erdwärmezeitung.de it is a widely spread mistake, that these system shall be the most efficient ones. The performance of the delivery pump is, amongst others, very decisive for the system efficiency. Also these devices are subject to an increased amount of maintenance, as e.g. the cleaning of the well (minerals in the water), the filter (sand circulation), the well pump (wear) and the heat exchanger in the heat pump.
The pretended “advantage“ of the high source temperatures and therewith high performance figures (test facility), not to be mistaken with the operating factor, can be turned into the opposite with a high input power of the delivery pump. Systems with wells have to overcome the delivery height (unsteady, lowered ground-water level), which costs energy. Geothermal probes only have to overcome the resistance of the geothermal probe system, which is constant and requires a low input power of the circulation pump. If all factors are right, the water-water heat pump systems can reach very high operating figures, too.
To make the gold mine on your land and the energy source for the future accessible, it has to be planned and constructed with highest possible expertise and accuracy. We recommend every building owner to ask all participants for the evidence of such expertise. References and certificates from different surveillance institutions should be the basic requirements for the placement of an order.
Silvio Klenner Erdwärme-Zeitung.de
